Hydrangea plant named ‘H218918’

ABSTRACT

A new and distinct cultivar of Hydrangea plant named ‘H218918’, characterized by its upright and uniformly mounded plant habit; vigorous growth habit and rapid growth rate; freely branching habit with strong, thick and sturdy stems; freely and uniformly flowering habit; mophead-type inflorescences with numerous incurved red purple- colored sterile flowers; and good postproduction longevity.

Botanical designation: Hydrangea macrophylla.

Cultivar denomination: ‘H218918’.

BACKGROUND OF THE INVENTION

The present invention relates to a new and distinct cultivar ofHydrangea plant, botanically known as Hydrangea macrophylla,commercially referred to as a mophead-type Hydrangea and hereinafterreferred to by the name ‘H218918’.

The new Hydrangea plant is a product of a planned breeding programconducted by the Inventor in De Kwakel, The Netherlands and Lengerich,Germany. The objective of the breeding program was to create new strongand freely-branching Hydrangea plants with strong sturdy stems, uniformflowering habit, large inflorescences with numerous showy sterileflowers, attractive sterile flower color and good postproductionlongevity.

The new Hydrangea plant is a naturally-occurring whole plant mutation ofHydrangea macrophylla ‘Agrihydradrie’, disclosed in U.S. Plant Pat. No.19,726. The new Hydrangea plant was discovered and selected by theInventor as a single flowering plant from within a population of plantsof ‘Agrihydradrie’ in a controlled greenhouse environment in Lengerich,Germany in March, 2015.

Asexual reproduction of the new Hydrangea plant by vegetative tipcuttings in a controlled environment in De Kwakel, The Netherlands sinceApril, 2016 has shown that the unique features of this new Hydrangeaplant are stable and reproduced true to type in successive generations.

SUMMARY OF THE INVENTION

Plants of the new Hydrangea have not been observed under all possiblecombinations of environmental conditions and cultural practices. Thephenotype may vary somewhat with variations in environmental conditionssuch as temperature and light intensity without, however, any variancein genotype.

The following traits have been repeatedly observed and are determined tobe the unique characteristics of ‘H218918’. These characteristics incombination distinguish ‘H218918’ as a new and distinct Hydrangea plant:

-   -   1. Upright and uniformly mounded plant habit.    -   2. Vigorous growth habit and rapid growth rate.    -   3. Freely branching habit with strong, thick and sturdy stems.    -   4. Freely and uniformly flowering habit.    -   5. Large mophead-type inflorescences with numerous incurved red        purple-colored sterile flowers.    -   6. Good postproduction longevity.

Plants of the new Hydrangea can be compared to plants of the mutationparent, ‘Agrihydradrie’. Plants of the new Hydrangea differ primarilyfrom plants of ‘Agrihydradrie’ in sterile flower form as sterile flowersof plants of the new Hydrangea have incurved sepals whereas sterileflowers of plants of ‘Agrihydradrie’ have flat sepals. In addition,plants of the new Hydrangea have flatter inflorescences than plants of‘Agrihydradrie’.

Plants of the new Hydrangea can be compared to plants of the Hydrangeamacrophylla ‘HBA215911’, disclosed in U.S. Plant Pat. No. 29,220. Inside-by-side comparisons, plants of the new Hydrangea differ primarilyfrom plants of ‘HBA215911’ in the following characteristics:

-   -   1. Plants of the new Hydrangea have larger inflorescences than        plants of ‘HBA215911’.    -   2. Sterile flowers of plants of the new Hydrangea have incurved        sepals whereas sterile flowers of plants of ‘HBA215911’ have        flat sepals.

BRIEF DESCRIPTION OF THE PHOTOGRAPHS

The accompanying colored photographs illustrate the unique appearance ofthe new Hydrangea plant showing the colors as true as it is reasonablypossible to obtain in colored reproductions of this type. Colors in thephotographs may differ from the color values cited in the detailedbotanical description which accurately describe the colors of the newHydrangea plant.

The photograph on the first sheet is a side perspective view of atypical flowering plant of ‘H218918’.

The photograph on the second sheet is a close-up view of a typicalinflorescence of ‘H218918’.

The photograph on the third sheet is a top perspective view of a typicalflowering plant of ‘H218918’ that has been “blued” (left) that is,treated with aluminum sulfate, and a top perspective view of a typicalflowering plant of ‘H218918’ that has not been “blued” (right) that is,not treated with aluminum sulfate.

DETAILED BOTANICAL DESCRIPTION

Plants used in the aforementioned photographs and in the followingdescription were grown during the late spring and early summer in 13-cmcontainers in a glass-covered greenhouse in De Kwakel, The Netherlandsand under cultural practices typical of commercial Hydrangea production.During the production of the plants, day and night temperatures averaged17° C. Plants of the new Hydrangea were one year old when thephotographs and description were taken. Plants of the new Hydrangea canbe successfully treated with aluminum sulfate to “blue” theinflorescences. In the following description, color references are madeto The Royal Horticultural Society Colour Chart, 2015 Edition, exceptwhere general terms of ordinary dictionary significance are used.

-   Botanical description: Hydrangea macrophylla ‘H218918’.-   Parentage: Naturally-occurring whole plant mutation of Hydrangea    macrophylla ‘Agrihydradrie’, disclosed in U.S. Plant Pat. No.    19,726.-   Propagation:    -   -   Type cutting.—By vegetative tip cuttings.        -   Time to initiate roots, summer.—About two weeks at            temperatures about 23° C.        -   Time to initiate roots, winter.—About 18 days at            temperatures about 20° C.        -   Time to produce a rooted young plant, summer.—About four            weeks at temperatures about 23° C.        -   Time to produce a rooted young plant, winter.—About five            weeks at temperatures about 20° C.        -   Root description.—Thick; typically whitish brown in color,            actual color of the roots is dependent on substrate            composition, water quality, fertilizer type and formulation,            substrate temperature and physiological age of roots.        -   Rooting habit.—Freely branching; dense.-   Plant description:    -   -   Plant and growth habit.—Upright and uniformly mounded plant            habit; strong and sturdy stems; rapid growth rate and            vigorous growth habit.        -   Plant height.—About 20 cm to 30 cm.        -   Plant diameter or area of spread.—About 55 cm to 60 cm.-   Lateral branch description:    -   -   Branching habit.—Freely branching habit; when pinched, about            eight to eleven lateral branches develop per plant.        -   Length.—About 20 cm.        -   Diameter.—About 6 mm.        -   Internode length.—About 2.5 cm to 4 cm.        -   Texture.—Smooth, glabrous; fully developed, woody.        -   Aspect.—Upright to about 20° from vertical.        -   Strength.—Strong, sturdy.        -   Color.—When developing: Close to 144B; at internodes, close            to 187A; lenticels, close to 187A. Developed: Close to 144B;            at the internodes, close to 187A; when woody, close to 177D;            lenticels, close to 187A.-   Leaf description:    -   -   Arrangement.—Opposite, simple.        -   Length.—About 7 cm to 10 cm.        -   Width.—About 6 cm to 8 cm.        -   Shape.—Ovate.        -   Apex.—Acuminate to cuspidate.        -   Base.—Obtuse.        -   Margin.—Dentate to serrate.        -   Texture, upper surface.—Smooth, glabrous.        -   Texture, lower surface.—Rugose, glabrous.        -   Venation pattern.—Pinnate.        -   Color.—Developing and fully expanded leaves, upper surface:            Close to NN137B; venation, close to 145B. Developing and            fully expanded leaves, lower surface: Close to 138B;            venation, close to 145C.        -   Petioles.—Length: About 2 cm to 2.5 cm. Diameter: About            3 mm. Texture, upper and lower surfaces: Smooth, glabrous.            Color, upper surface: Close to 145B. Color, lower surface:            Close to 145C.-   Flower description:    -   -   Flower type and habit.—Showy sterile flowers and small            inconspicuous fertile flowers arranged on mophead-type            terminal panicles; panicles globular in shape; flowers face            upright to outwardly depending on their position in the            inflorescence.        -   Fragrance.—None detected.        -   Natural flowering season.—Plants begin flowering about three            months after planting; flowering begins in the early summer            and is continuous throughout the summer in Northern Europe.        -   Flower longevity.—Fertile flowers last about one month on            the plant, fertile flowers not persistent; sterile flowers            last about four months on the plant, sterile flowers            persistent.        -   Quantity of flowers.—Freely flowering habit; about 60            fertile flowers per panicle and about 130 sterile flowers            per panicle.        -   Panicle height.—About 6 cm to 7 cm.        -   Panicle diameter.—About 16 cm to 20 cm.        -   Fertile flower buds.—Length: About 3 mm. Diameter: About            3 mm. Shape: Flattened globular. Color: Close to N57D and            145C.        -   Sterile flower buds.—Length: About 3 mm. Diameter: About            3 mm. Shape: Flattened globular. Color: Close to N57D and            145C.        -   Fertile flower diameter.—About 6 mm.        -   Fertile flower depth (height).—About 5 mm.        -   Sterile flower diameter.—About 2 cm to 2.5 cm.        -   Sterile flower depth (height).—About 3 cm.        -   Petals, fertile flowers.—Quantity and arrangement: Four in a            single whorl. Length: About 3.5 mm. Width: About 2 mm.            Shape: Ovate. Apex: Acute. Base: Obtuse. Margin: Entire.            Texture, upper and lower surfaces: Smooth, glabrous. Color:            When opening, upper and lower surfaces: Close to N57D and            144D. Fully opened, upper and lower surfaces: Close to N57D            and 144D; color does not change with development.        -   Petals, sterile flowers.—Quantity and arrangement: Four in a            single whorl. Length: About 3 mm. Width: About 3 mm. Shape:            Ovate. Apex: Acute. Base: Obtuse. Margin: Entire. Texture,            upper and lower surfaces: Smooth, glabrous. Color: When            opening, upper and lower surfaces: Close to 145D. Fully            opened, upper and lower surfaces: Close to N57D; color does            not change with development.        -   Sepals, fertile flowers.—Quantity and arrangement: Five in a            single whorl. Length: About 2 mm. Width: About 2 mm. Shape:            Ovate. Apex: Acute. Base: Obtuse. Margin: Entire. Texture,            upper and lower surfaces: Smooth, glabrous. Color: When            opening, upper and lower surfaces: Close to 144C. Fully            opened, upper and lower surfaces: Close to 144D; color does            not change with development.        -   Sepals, sterile flowers.—Quantity and arrangement: Four in a            single whorl. Length: About 1 cm to 1.5 cm. Width: About 1            cm to 1.5 cm. Shape: Ovate, incurved. Apex: Obtuse. Base:            Obtuse. Margin: Entire. Texture, upper surface: Smooth,            glabrous. Texture, lower surface: Rugose, glabrous. Color:            When opening and fully opened, upper surface: Close to N57B            and towards the base, close to 157B, and venation close to            N57D; with development, color becoming closer to 187A and            146B; when “blued”, close to 186D towards the base, close to            145A to 145C, and edges, close to N79D. When opening and            fully opened, lower surface: Close to N57D; with            development, color becoming closer to 187B and 146C.        -   Pedicels, fertile flowers.—Length: About 4 mm. Diameter:            About 1 mm. Strength: Moderately strong. Aspect: Mostly            upright. Texture: Smooth, glabrous. Color: Close to 145B.        -   Pedicels, sterile flowers.—Length: About 2.5 cm to 3 cm.            Diameter: About 1.5 mm. Strength: Strong. Aspect: Erect to            about 45° from vertical. Texture: Smooth, glabrous. Color:            Close to N57D.        -   Reproductive organs, fertile flowers.—Stamens: Quantity per            flower: Eight. Filament length: About 1 mm. Filament color:            Close to 155D. Anther length: About 1 mm. Anther shape:            Conical. Anther color: Close to 145D. Pollen amount:            Abundant. Pollen color: Close to 155D. Pistils: Pistil            quantity per flower: Three. Pistil length: About 1 mm.            Stigma shape: Oval. Stigma color: Close to 186C. Style            length: About 1 mm. Style color: Close to 145B. Ovary color:            Close to 145B.        -   Reproductive organs, sterile flowers.—Stamens: Quantity per            flower: About five to eight. Filament length: About 2 mm.            Filament color: Close to 155D. Anther length: About 1 mm.            Anther shape: Conical. Anther color: Close to 145D. Pollen            amount: Abundant. Pollen color: Close to 155D. Pistils:            Pistil quantity per flower: Three. Pistil length: About            2 mm. Stigma shape: Conical. Stigma color: Close to 155C.            Style length: About 1 mm. Style color: Close to 155C. Ovary            color: Close to 155C.        -   Seeds, only produced by fertile flowers.—Quantity per            fertile flower: About 20 to 30. Length: About 0.5 mm.            Diameter: About 0.1 mm. Color: Close to 200C.-   Pathogen & pest resistance: Under commercial production conditions,    plants of the new Hydrangea have not been observed to be resistant    to pathogens and pests common to Hydrangea plants to date.-   Temperature tolerance: Plants of the new Hydrangea have been shown    to be tolerant to temperatures ranging from about 3° C. to about 38°    C.

It is claimed:
 1. A new and distinct Hydrangea plant named ‘H218918’ asillustrated and described.